164 Animal Intelligence 
at different ages, because it seemed rather cruel and degrad- 
ing to the experimenter. When in the case of the older chicks 
nature happened to make the experiment, it was hard to de- 
cide whether there was more violent fear of the jumping cat 
than there was when one threw a basket or football into the 
pen. There was not very much more. 
We may now proceed to a brief recital of the facts shown 
by the experiments in so far as they are novel. It should be 
remembered throughout that in every case chicks of differ- 
ent ages were tested so as to demonstrate transitory in- 
stincts if such existed, e.g., the presence of a fear of flame 
was tested with chicks 59 and 60, one day old, 30 and 32, two 
days old, 21 and 22, three days old, 23 and 24, seven days 
old, 27 and 29, nine days old, 16 and 19, eleven days old, 
and so on up to twenty-days-old chicks. By thus using 
different subjects at each trial one, of course, eliminates any 
influence of experience. 
The first notable fact is that there develops in the first 
month a general fear of novel objects in motion. For four 
or five days there seems to be no such. You may throw a 
hat or slipper or shaving mug at a chick of that age, and he 
will do no more than get out of the way of it. But a twenty- 
five-days-old chick will generally chirr, run and crouch for 
five or ten seconds. My records show this sort of thing be- 
ginning about the tenth day, but it is about ten days more 
before it is very marked. In general, also, the reaction is 
more pronounced. if many chicks are together, and is then 
displayed earlier (only two at a time were taken in the ex- 
periments the results of which have just been quoted). 
Thus the reaction is to some degree a social performance, the 
presence of other chicks combining with the strange object 
to increase the vigor of the reaction. Chicks ordinarily 
scatter.apart when they thus run from an object. 
